A method and a device for controlling an internal combustion engine having an exhaust treatment system is described in German Published Patent Application No. 199 06 287. The system described in this document uses a particle filter that filters out particles contained in the exhaust gas. To precisely control an internal combustion engine having an exhaust treatment system, the status of the exhaust treatment system must be known. In particular, the filter's state of congestion, i.e., the volume of filtered-out particles, must be known.
It is an object of the present invention to provide a method and a device that can be used to detect the status of the exhaust treatment system. In particular, the state of congestion must be detected even when different sensors fail or when no special sensors are used.